Ruthenium-optically active phosphine complex, process for the preparation thereof and process for the preparation of optically active 4-methyl-2-oxetanone using same

Abstract

The present invention provides a catalyst which exhibits a high catalytic activity and allows asymmetric reaction in a high asymmetric yield to obtain a reaction product having a high optical purity. The present invention also provides a process for the preparation of an optically active 4-methyl-2-oxetanone having a high optical purity useful as starting material of polymer in a high yield in a short period in the presence of the foregoing catalyst. A novel ruthenium-iodo-optically active phosphine complex is provided, represented by the following general formula (1): Ru--I.sub.2 -(R.sup.1 -BINAP) (1) wherein R 1 -BINAP represents an optically active tertiary phosphine represented by the following general formula (2): ##STR1## wherein R 1 represents an aryl group which may have a substituent selected from the group consisting of a C 1-4 lower alkyl group, a C 1-4 lower alkoxy group, a C 1-4 lower alkylamino group, and a halogen atom or a C 3-8 cycloalkyl group.

What is claimed is: 
     
       1. A process for the preparation of an optically active 4-methyl-2-oxetanone, which comprises the asymmetric hydrogenation of 4-methylene-2-oxetanone in the presence of as a catalyst a ruthenium-iodo-optically active phosphine complex represented by the following general formula (1):   Ru--I.sub.2 -(R.sup.1 -BINAP)                              (1)     wherein R 1  -BINAP represents an optically active tertiary phosphine represented by the following general formula (2): ##STR4## wherein R 1  represents an aryl group which may have a substituent selected from the group consisting of a C 1-4  lower alkyl group, a C 1-4  lower alkoxy group, a C 1-4  lower alkylamino group, and a halogen atom or a C 3-8  cycloalkyl group.   
     
     
       2. The process for the preparation of an optically active 4-methyl-2-oxetanone according to claim 1, wherein said ruthenium-iodo-optically active phosphine complex is obtained by any one of the following three preparation processes (A)-(C): (A) a process which comprises allowing a ruthenium-optically active phosphine complex represented by the following general formula (3):   RuI(arene)(R.sup.1 -BINAP)]I                               (3)     wherein (arene) represents a hydrocarbon having benzene ring: and R'-BINAP is as earlier defined: to undergo reaction in a polar solvent;     (B) a process which comprises allowing an optically active phosphine represented by the following general formula (4):   [RuI.sub.2 (arene)].sub.2                                  ( 4)     wherein (arene) represents a hydrocarbon having benzene ring and the optically active tertiary phosphine represented by the general formula (2) to undergo reaction in a polar solvent; or     (C) a process which comprises allowing a ruthenium-optically active phosphine complex represented by the following general formula (5):   Ru(R.sup.2 COO).sub.2 (R.sup.1 -BINAP)                     (5)       wherein R 2  represents a hydrogen atom, a lower alkyl group, a halogenated lower alkyl group or an aryl group which may have a lower alkyl substituent, and R 1  -BINAP is as earlier defined; to undergo reaction with hydroborofluoric acid and an inorganic iodide.     
     
     
       3. The process for the preparation of an optically active 4-methyl-2-oxetanone according to claim 1, wherein said ruthenium-iodo-optically active phosphine complex shows one or two doublets within a 8 range of from -1 to 12 ppm and one or two doublets within a δ range of from 66 to 81 ppm when subjected to  31  P-NMR.